Printed Circuit Design & Fab Online Magazine - Current Issue

Current Issue

Smooth copper isn't always what it is purported to be.

I always trusted datasheets. Why shouldn't I? Every time I picked one up, I understood they were harbingers of truth about what something did and how to interact with it. From chips to components to widgets, manufacturers have a vested interest in ensuring users know what and how to use their products.

My trust in datasheets was eviscerated the very week I entered the printed circuit board industry. I was attending a weeklong training session on signal integrity taught by Eric Bogatin when he surveyed the attendees about datasheets and their accuracy. While my memory of the day and exact content isn't perfect, I do recall that as the very moment I learned the harsh reality: Datasheets are sometimes not as accurate as one would hope! (As an aside, Eric Bogatin's books on signal integrity are excellent resources because he has that special gift of teaching and explaining complex topics in approachable and understandable ways. The concept of "being the signal" and walking down a transmission line is just fantastic.)

Read more: GD&T and PCBs

Jeffrey Beauchamp Why a relatively unknown technology might be right for static bend applications.

Working with semi-flexible PCBs has opened some unique opportunities that I believe are worth exploring. The idea behind semi-flex is simple yet effective: a circuit that can flex without the high cost associated with using polyimide materials, which are typically necessary for full flexibility. This means the PCB can handle moderate bending without the expense of materials traditionally required for a fully flexible circuit. In multiple scenarios, once I’ve introduced this technology to customers, they’ve fully embraced it and have incorporated it into their PCB designs many times over, replacing rigid-flex designs for limited or static bend applications.

Despite the advantages, semi-flex is still a relatively unknown technology. A small group of people understand what it is and use it regularly, but for most, it’s completely new, and they’re often amazed by the possibilities it brings. Many customers light up when they see how a semi-flexible circuit could work in their applications, especially since it brings flex into the rigid realm. This permits flexible applications while leveraging the manufacturing techniques of a typical multilayer or HDI factory. It’s a major advantage because, unlike fully flexible PCBs, semi-flexible boards don’t require specialized facilities, which can drive up costs and narrow production options.

Read more: Semi-Flexible PCBs: Flexibility without the Polyimide Price Tag